GENERAL STRUCTURE AND ORDERS. 



I03I 



bony in many of the other genera. The following genera from the 

 Permian of Europe have vertebrae agreeing in structure with those of 

 the typical forms, and may be provisionally placed in the same fam- 

 ily; they are named Melosaurus, Osteophorus, Zygosaurus, Chelydosan- 

 rus, Cochkosaurus, Gaudrya, Acti?iodon, and Enchirosaurus. Sphe?io- 

 saurus, from the Permian of Bohemia, has also been placed here, 

 although some writers regard it as a Reptile. The name Disco- 

 saurus has also been applied to a member of this group from the 



Fig. 961. — Upper surface of the skull (a), and ventral scutes (b) of Cricotus heteroclitus ; from 

 the Permian of North America. One-half natural size. (After Cope.) 



Permian of Dresden, but it is preoccupied in the Sauropterygia. 

 Portions of a vertebra of JEuchi?'osaurus, from Autun in France, are 

 shown in fig. 960, the neural spine being remarkable for the great 

 lateral expansion of its summit ; according to Dr Fritsch's restora- 

 tion (fig. 956) the pleurocentra belonging to this vertebra would be 

 on the anterior side, but Dr Zittel would rather regard those on the 

 posterior aspect as referable to this segment of the column. In 

 the Bijori stage of the Lower Gondwanas of India this group is 



VOL. II. K 



